Looking for some advise about waves

Hi all,

Just a question about waves. I have just completed all 6 hour waves I can do, the next thing to do is to now extend further. My question is do I stick with everything in 6 hour waves, say 1 flight to a destination is 4 hours there and 4 hours back, do I then let the plane sit for 4 hours until it fits back into my 6 hour waves?

Sorry I hope that all makes sense, thank you.